The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Generally, eco-friendly vehicles such as a hybrid electric vehicle (HEV) and an electric vehicle (EV) are configured to include an engine control unit (ECU) controlling an engine, a motor control unit (MCU) controlling motor driving, a transmission control unit (TCU) controlling a shift of a transmission, a battery management system (BMS) monitoring and managing a battery state, and a hybrid control unit (HCU) controlling the driving of the control units, setting a driving mode of the vehicles, and controlling the general driving of the vehicles.
A vehicle controller is connected to each control unit through a controller area network (CAN) communication line, a local interconnect network communication line, and so on to transmit and receive data. Therefore, when there is a problem in the CAN communication of the battery controller, other control units may not confirm a state of charge (SOC) of a main battery. When the state of charge of the main battery may not be confirmed, the vehicle controller restricts the charging and discharging of the battery and controls the engine driving using the engine control unit, and thus the vehicle may be driven in a limp home mode.
The vehicle inevitably consumes a minimum current for driving even during the limp home driving based on the engine driving, and therefore the battery is discharged. For example, power is consumed to drive a low voltage DC-DC converter (LDC), an external auxiliary (AUX), an electric oil pump, and so on.
The battery controller forcibly opens a main battery relay to prevent the battery from being damaged at the time of overdischarging of the main battery due to the limp home driving, such that an operation of the electric oil pump stops and an oil pressure of the transmission is not yet formed. As a result, the vehicle may not be driven.